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<li class="toctree-l1"><a class="reference internal" href="../metadata/index.html"> 元数据</a><ul>
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<li class="toctree-l2"><a class="reference internal" href="../security/cdap-authentication-clients-java.html">CDAP Authentication Client for Java</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../testing/testing.html"> Testing a CDAP Application</a></li>
<li class="toctree-l2"><a class="reference internal" href="../testing/debugging.html"> Debugging</a></li>
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<li class="toctree-l1"><a class="reference internal" href="../ingesting-tools/index.html"> 数据融合</a><ul>
<li class="toctree-l2"><a class="reference internal" href="../ingesting-tools/cdap-stream-clients-java.html">CDAP Stream Client for Java</a></li>
<li class="toctree-l2"><a class="reference internal" href="../ingesting-tools/cdap-stream-clients-python.html">CDAP Stream Client for Python</a></li>
<li class="toctree-l2"><a class="reference internal" href="../ingesting-tools/cdap-stream-clients-ruby.html">CDAP Stream Client for Ruby</a></li>
<li class="toctree-l2"><a class="reference internal" href="../ingesting-tools/cdap-flume.html">CDAP Flume</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../data-exploration/filesets.html"> Fileset Exploration</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../advanced/application-logback.html"> Application Logback</a></li>
<li class="toctree-l2"><a class="reference internal" href="../advanced/best-practices.html"> Best Practices</a></li>
<li class="toctree-l2"><a class="reference internal" href="../advanced/class-loading.html"> Class Loading</a></li>
<li class="toctree-l2"><a class="reference internal" href="../advanced/configuring-resources.html"> Configuring Program Resources</a></li>
<li class="toctree-l2"><a class="reference internal" href="../advanced/program-retry-policies.html"> Program Retry Policies</a></li>
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      </li>
      <li class="toctree-l1"><a href="../table-of-contents/../../admin-manual/index.html" rel="nofollow">管理手册</a>
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      <li class="toctree-l1"><a href="../table-of-contents/../../integrations/index.html" rel="nofollow">集成手册</a>
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      <li class="toctree-l1"><a href="../table-of-contents/../../examples-manual/index.html" rel="nofollow">最佳实践</a>
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  </div></div>
    </div><div class="col-md-8 content" id="main-content">
    
  <div class="section" id="building-blocks">
<span id="id1"></span><h1>核心概念<a class="headerlink" href="#building-blocks" title="Permalink to this headline">🔗</a></h1>
<div class="toctree-wrapper compound">
<ul>
<li class="toctree-l1"><a class="reference internal" href="core.html"> Core Abstractions</a></li>
<li class="toctree-l1"><a class="reference internal" href="applications.html"> Applications</a></li>
<li class="toctree-l1"><a class="reference internal" href="datasets/index.html"> Datasets</a></li>
<li class="toctree-l1"><a class="reference internal" href="mapreduce-programs.html"> MapReduce Programs</a></li>
<li class="toctree-l1"><a class="reference internal" href="plugins.html"> Plugins</a></li>
<li class="toctree-l1"><a class="reference internal" href="schedules.html"> Schedules</a></li>
<li class="toctree-l1"><a class="reference internal" href="secure-keys.html"> Secure Keys</a></li>
<li class="toctree-l1"><a class="reference internal" href="services.html"> Services</a></li>
<li class="toctree-l1"><a class="reference internal" href="spark-programs.html"> Spark Programs</a></li>
<li class="toctree-l1"><a class="reference internal" href="workers.html"> Workers</a></li>
<li class="toctree-l1"><a class="reference internal" href="workflows.html"> Workflows</a></li>
<li class="toctree-l1"><a class="reference internal" href="artifacts.html"> Artifacts</a></li>
<li class="toctree-l1"><a class="reference internal" href="program-lifecycle.html"> Program Lifecycle</a></li>
<li class="toctree-l1"><a class="reference internal" href="namespaces.html"> Namespaces</a></li>
<li class="toctree-l1"><a class="reference internal" href="transaction-system.html"> Transaction System</a></li>
<li class="toctree-l1"><a class="reference internal" href="transactional-messaging-system.html"> Transactional Messaging System</a></li>
</ul>
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<div class="toctree-wrapper compound">
</div>
<p>This section covers the <a class="reference internal" href="core.html"><span class="doc">core abstractions</span></a> in the Cask Data Application Platform
(CDAP): <strong>Data</strong> and <strong>Applications.</strong></p>
<p>An <a class="reference internal" href="applications.html"><span class="doc">Application</span></a> is a collection of application building blocks that read and
write data through the data abstraction layer in CDAP.</p>
<p><strong>Data abstractions</strong> include:</p>
<ul class="simple">
<li><a class="reference internal" href="datasets/index.html"><span class="doc">Datasets</span></a></li>
</ul>
<p><strong>Applications</strong> are composed from these program building blocks:</p>
<ul class="simple">
<li><a class="reference internal" href="mapreduce-programs.html"><span class="doc">MapReduce Programs</span></a></li>
<li><a class="reference internal" href="plugins.html"><span class="doc">Plugins</span></a></li>
<li><a class="reference internal" href="schedules.html"><span class="doc">Schedules</span></a></li>
<li><a class="reference internal" href="services.html"><span class="doc">Services</span></a></li>
<li><a class="reference internal" href="spark-programs.html"><span class="doc">Spark Programs</span></a></li>
<li><a class="reference internal" href="workers.html"><span class="doc">Workers</span></a></li>
<li><a class="reference internal" href="workflows.html"><span class="doc">Workflows</span></a></li>
</ul>
<p><strong>Additional abstractions</strong> include:</p>
<ul class="simple">
<li>An <a class="reference internal" href="artifacts.html"><span class="doc">Artifact</span></a> is a jar file that packages the Java Application class, as well
as any other classes and libraries needed to create and run an Application.</li>
<li>All of the program building blocks follow a <a class="reference internal" href="program-lifecycle.html"><span class="doc">Program Lifecycle</span></a>.</li>
<li><a class="reference internal" href="../metadata/index.html#metadata"><span class="std std-ref">Metadata</span></a>—consisting of <strong>properties</strong> (a list of key-value pairs)
or <strong>tags</strong> (a list of keys)—can be set for artifacts, applications, programs, and datasets.
These can be retrieved and searched, and the metadata used to discover CDAP entities.
Access of these entities is tracked, and you can view the <a class="reference internal" href="../metadata/discovery-lineage.html#metadata-lineage"><span class="std std-ref">lineage</span></a> of datasets.
With a lineage diagram, you can then drill down into the metadata of its nodes.</li>
<li><a class="reference internal" href="../metadata/audit-logging.html#audit-logging"><span class="std std-ref">Audit Logging</span></a> provides a chronological ledger containing evidence of operations or
changes on CDAP entities. This information can be used to capture a trail of the activities that
determined the state of an entity at a given point in time.</li>
<li>A <a class="reference internal" href="namespaces.html"><span class="doc">Namespace</span></a> is a logical grouping of application and data in CDAP.
Conceptually, namespaces can be thought of as a partitioning of a CDAP instance.
All applications and data live in an explicit CDAP namespace.</li>
<li>The <a class="reference internal" href="transaction-system.html"><span class="doc">Transaction System</span></a> is an essential service
that provides ACID (<em>atomicity, consistency, isolation,</em> and <em>durability</em>) guarantees,
critical in applications where data accuracy is required.</li>
<li>The <a class="reference internal" href="transactional-messaging-system.html"><span class="doc">Transactional Messaging System</span></a> is a CDAP service
that provides a “publish-and-subscribe” messaging system that understands transactions.</li>
<li><a class="reference internal" href="secure-keys.html"><span class="doc">Secure Keys</span></a> allows users to store and retrieve sensitive information such
as passwords from secure and encrypted storage.</li>
</ul>
<p>For a <strong>high-level view of the concepts</strong> of the Cask Data Application Platform, see the
platform <a class="reference internal" href="../overview/index.html"><span class="doc">overview.</span></a></p>
<p>For information beyond this section, see the <span class="xref std std-ref">Javadocs</span>, which are available
at the <a class="reference external" href="http://cask.co/resources">Cask.co resources page,</a>.</p>
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